Moving stairway



Feb. 11', 1941. J. DUNLOP 2,231,709

MOVING STAIRWAY Filed June 18, 1940 2 Sheets-Sheet l 'IIIIIIIIIII 44 WITNESSES: INV ENTOR Feb. 11, 1941. J. D-UNLOP 2,231,709

MOVING sTAIRwAi I Filed June 18, 1940 v 2 Sheets-Sheet 2 WITNESSES: INVENTOR M. Jamesflunlop.

Patented Feb. 11, 1941 UNITED STATES PATENT OFFICE MOVING STAIRWAY Application June 18, 1940, Serial No. 341,084

8 Claims.

My invention relates to moving Stairways, and more particularly, to means for operating the stairway steps along their tracks.

In moving Stairways as heretofore constructed,

: the steps have been supported upon their tracks by front rollers and by rear rollers, and have been moved along their tracks by driving chains which pass around driving sprocket wheels at the ends of the stairways. The steps are fastened to the chains by passing the front axles through the roller joints in the chains. In order to keep the amount of sagging of the chains between the steps as low as possible, they are kept under tension by means of suitable tensioning mechanism connecting the lower sprocket wheels to the lower end of the stairway frame.

It is also customary to provide suitable guide rails above the step rollers to limit the degree to which they may leave their track rails and to an avoid objectionable tilting of the steps. In constructing the stairway, the guide rails and the track rails are mounted in position with a minimum amount of clearance between them for the step rollers. However, where the steps leave the 25 lower landing and curve toward the straight rise portion of the stairway extending to the upper landing, the tension on the chains tends to cause them to raise the front axles of the steps, thus moving the rollers thereon upwardly from their sotrack rails into engagement with their guide rails.

When the steps are new, the clearance between the track rails and the guide rails may be so small that the free play of the rollers therebetween will not be noticeable. However, as the steps continue in operation, the step rollers wear from their normal full size to a smaller size and hence the amount of clearance between them and the rails becomes greater. If the wear becomes excessive, there is a tendency for the steps to increase their float or tilt and operate in an unpleasant manner as they move along the tracks. I-Ieretofore the only way to overcome this unpleasant kind of operation has been to replace the worn rollers with new rollers.

One object of my invention is to provide a stairway in which it will not be necessary to renew any rollers which are only slightly worn in order to eliminate any unpleasant features in riding the steps.

50' Another object is to cause the steps to move in a definite path unaffected by the weight and position of the passenger load.

Another object of my invention is to provide a moving stairway in which the steps will glide from one landing to another without tilting or deviating even slightly from the path along which they are designed to travel, regardless of wear of the parts.

A further object of my invention is to provide a moving stairway construction in which less care 5 will be required in positioning the guide rails over the track rails than has heretofore been required.

It is also an object of my invention to provide a moving stairway in which the step rollers will in be biased into contact with their track rails at the curved section on their upper runway between the lower landing and the straight rise to the upper landing.

For a better understanding of my invention, reference may be had to the accompanying drawings, in which:

Figure l is a diagrammatic representation of one side of a moving stairway embodying my invention, as seen from the interior of the stairy;

Fig. 2 is an enlarged View, in side elevation, of the curved portion of the stairway leading from the lower landing to the straight rise portion of the stairway with my improved step biasing '25 means embodied therein;

Fig. 3 is a view in side elevation of a portion of the left-hand end of Fig. 2, with parts of the sprocket chain and the steps broken away to permit illustration of the biasing rail; and g5 Fig. 4 is a view in cross-sectionof the front axle, driving chain, and front rollers of a step with the biasing cam on each side disposed in engagement with the chain rollers.

Referring more particularly to the drawings, I have illustrated a moving stairway as comprising an endless series of movable steps ll disposed to be moved along a track l2 by a pair of sprocket chains l3 and 14 between an upper landing I5 and a lower landing Hi. The sprocket E chains are supported at the upper landing by a pair of driving sprocket wheels I1, and at the lower landing by a pair of tensioning sprocket wheels I8. A tension device [9 is illustrated as 4 attached to the axle 20 of the lower sprocket 4'5 wheels [8 to bias the tensioning sprocket wheels to the right to maintain the sprocket chains under a suitable tension at all times.

Each of the chains comprises a plurality of outer links 23 and 24 and a plurality of inner 66 links 25 and 26 connected at each joint by-a cross pin 21. A roller 28 is rotatably mounted upon each cross pin for the purpose of engaging the sprocket teeth as the chain operates over the sprocket wheels. Each roller 28 is' provided with a central peripheral channel 29 and side flanges 30 and 3! to cause it to seat securely on the sprocket wheels. A front axle 32 and a pair of rear stub axles 32a are mounted on each step. The ends of the front axle extend through bushings 21a in adjacent joints in the chains so that the steps will move along their tracks with the movement of the chains.

Each step is supported on its track by a pair of front wheels or rollers 33 and 34 (Fig. 4) mounted on the outer ends of its front axle 32 and a pair of trailing wheels or rollers 35 mounted on its rear stub axles 32a. In moving on the upper track from the lower landing to the upper landing, the front roller 34 travels on a track rail 36 comprising an angle iron suitably mounted upon a channel iron 3?. The front roller 33 is likewise provided with a track rail 33 mounted upon the channel bar 33. The rear wheels 35 run on a track rail 35a.

A plurality of horizontally mounted rollers 43 are disposed on the channel members 3'! and 39 by means of supporting bases 4| in position to engage the inner surfaces of the front step rollers and thereby prevent the steps from moving laterally while they travel along the track.

A guard rail 44 is mounted above the wheel 34 on a member of the stairway framework 45 for the purpose of preventing the wheel from leaving the track rail 3%. When the stairway is constructed, the guide rail 44 is disposed very close to the roller 34, particularly at the point in the stairway where the steps leave the lower landing and curve upwardly toward the upper landing in order to prevent the tensioning of the chains from pulling the front end of the step upwardly. However, the clearance between the guide rail 44 and the step roller 34 must be sufficient to permit the roller to trave1 along its track rail 36 without rubbing against the guide rail. A similar guide rail 44a is provided for the front rollers 33.

When the stairway is new and the clearance between the guide rail and the wheel is very small, there will be a slight free play of the wheel between its track railand its guide rail, but the amount of this free play will be so small that it will not be very objectionable. However, it has been found in practice that the wheels wear to a smaller diameter and thereby increase the clearance between themselves and the guide rail to such an extent that an objectionable movement of the wheel between the track rail and the guard rail may occur, particularly at the point where the stairway curves upwardly from the lower landing toward the upper landing.

In order to avoid this difficulty, I have provided a means for biasing the front rollers of the steps toward their track rails while they are moving along the curved section of the track leading to the upper landing. The biasing means comprises a pair of flexible cam strips 47 and 41a disposed to engage the channel portions 29 of the rollers on the chain joints as the chains pass along the curved portion of the stairway leading upward from the lower landing to the straight rise portion of the stairway. The flexible cam member 41 may be constructed of any suitable material, such as a textile material impregnated with a phenolic condensation product capable of hardening under heat and pressure. This material, such as is sold under the trade-mark Micarta, will provide an effective wearing but quiet surface for engaging the chain rollers. The flexible cam strip is mounted upon a flexible strip of steel or other suitable material 48, backed up by a resilient means such as a plurality of coil compression springs 49 which bias the flexible cam strip into engagement with the chain rollers. The compression springs may be mounted on suitable spring seats 50 in position to rest against the under face of the framework 45. The flexible cam member is anchored at its upper end by a suitable spring 5|, one end of which is attached to the frame member 45 and the other end of which is attached to the front end of the biasing cam, to prevent undue longitudinal motion and to cause the cam to maintain its longitudinal position while the chain rollers pass under it.

Inasmuch as the springs 49 press the biasing cam strip downwardly on the chain rollers as the steps pass along the portion of the track to which the biasing cams are attached, it will be seen that they press the front rollers of the steps downwardly and firmly against their track rails 36 and 38, regardless of the upward pull the chains may exert upon the axle 32 by reason of the amount of tension in the chains. This prevents any binding on the rollers or the steps because the front wheels 33 and 34 rotate freely along their track rails 36 and 38 while the chain rollers 28 are free to rotate in the opposite direction as they travel along under the biasing cam. Inasmuch as the front rollers are pressed firmiy against their track rails, there will be no tendency for the front end of the step to float between its track rails and its guard rails, regardless of how much wear may occur in the step wheels. The trailing wheels or rollers 35 on the nose end of the step will, by reason of gravity, follow along their track rails 35a and hence the step will travel from the lower landing to the upper landing firmly along its track rails, regardless of the weight or distribution of the passengers on the stairway.

The strength of the biasing springs 49 and the stiffness of the biasing cam strip should be so selected that they will hold the front step wheels firmly enough on their tracks to prevent teetering or tilting of the steps when occupied by passengers and yet not so firmly as to cause any undue wear in the axles, rollers and flexible cam strip as the steps move along their runway.

By the foregoing construction it will be seen that the force exerted by the biasing cam strips bearing on the chain rollers as the steps pass along the upwardly curving portion of the stairway will press the front step wheels against their track rails, thus preventing the steps from floating between their track rails and guard rails while they are in the upwardly curving zone and thus eliminate any undesirable motion of the steps.

Although I have illustrated and described only one specific embodiment of my invention, it is to be understood that changes therein and modifications thereof may be made without departing from the spirit and scope of the invention.

I claim as my invention:

1. A moving stairway comprising an endless series of movable steps connecting a lower landing with an upper landing, a pairof rollers for each step, a track for the rollers, a framework for supporting the track and a resilient device mounted on the framework for applying resilient pressure to the structures of the steps as they move along a-portion of the. track for maintaining the rollers against said portion of the track.

2. A moving stairway comprising an endless series of movable steps connecting a lower landing with an upper landing, a pair of rollers for each step, a track for the rollers, a framework for supporting the track, a cam strip mounted on the framework above a portion of the track, and a resilient device acting loetween the framework and the cam strip to cause the cam strip to apply pressure for maintaining the rollers of the steps moving along said portion of the track against the track.

3. A moving stairway comprising an endless series of steps connecting a lower landing with an upper landing, a pair of rollers for each step, a track for the rollers, a framework for supporting the track, a chain for moving the steps along the track, and a cam strip mounted on the framework above the chain in position to engage the chain and force it toward the track for maintaining the rollers of the steps against the track.

4. A moving stairway comprising an endless series of steps connecting a lower landing with an upper landing, a pair of rollers for each step, a track for the rollers, a framework for supporting the track, a chain for moving the steps along the track, a cam strip mounted on the framework above the chain in position to engage the chain and force it toward the track for maintaining the rollers of the steps against the track, and resilient means acting between the framework and the cam strip for cushioning the pressure applied by the cam strip to the chain.

5. A moving stairway comprising an endless series of steps, axle means for each step, a pair of rollers mounted on the axle means, a track for the rollers, a framework for supporting the track, a chain attached to the axle means of each step for moving the steps along the track, and a resilient cam means mounted on the framework in position to apply a cushioned pressure to the chain as it passes along one portion of the track for. maintaining the rollers of the steps at that portion of the track against that portion of the track.

6. A moving stairway comprising an endless series of steps, axle means for each step, a pair of wheels mounted on the axle means for each step, a track for the wheels, a framework for supporting the track, a chain attached to the axle means of each step for moving the steps along the track, a cam strip attached to the frame in position to bear against the upper side of the chain for biasing the rollers against a portion of the track, and resilient means acting between the framework and the cam strip to cushion the action of the cam strip against the chain.

7. A moving stairway comprising an endless series of steps, axle means for each step, a pair of wheels, mounted on the axle means for each step, a track for the wheels, a framework for supporting the track, a chain attached to the axle means of each step for moving the steps along the track, a roller on each joint of the chain, a cam strip, and resilient means for attaching the cam strip to the framework in position to provide a cushioned pressure against the rollers on the chain as they pass along one portion of the track for maintaining the wheels against that portion of the track.

8. A moving stairway comprising an endless series of steps connecting a lower landing and an upper landing, axle means attached to each step, a pair of wheels mounted on each step, axle means, a track for the wheels curving from the lower landing toward a straight rise to the upper landing, a framework for supporting the track, a pair of sprocket Wheels at each landing, a pair of chains attached to the axle means at each side of each step and mounted on the sprocket wheels at one of the landings andextending to and passing around the sprocket wheels at the other landing for moving the steps along the track, a roller on each joint in the chains for facilitating their operation on the sprocket wheels, mechanism for maintaining the chains under tension to prevent sagging between the steps, and a cam strip mounted on the framework above said curved portion of the track in position to engage the rollers on the chain and bias them toward said curved portion of the track for maintaining the wheels in engagement with the track where it curves from the lower landing toward the straight rise to the upper landing.

JAMES DUNLOP. 

